a. General. Processing tanks are used for such operations as developing, rinsing,
fixing, washing, and drying x-ray films. Tanks as well as mixing vessels are usually made
of stainless steel. These tanks are the "wet side," and are usually used in manual
processing. In automatic processing, all of the processing tanks are in a closed
compressed unit, and require less maintenance than the manual tanks. The following
information will generally apply to manual processing.
b. Types. There are two general types of tanks in use:
(1) Master tank. The master tank serves as a water jacket for holding insert
tanks and usually provides space between the insert tanks for washing and rinsing. If a
washing tank is available, washing will be done in it.
(2) Insert tanks. Insert tanks are removable containers for individual solutions,
which are placed in the master tank. The stainless steel insert tanks are standardized at a
five-gallon capacity. The American Standards Association gives the inside dimensions of
a standard 5-gallon tank as 20-1/32 inches deep, 14-1/2 inches long, and four inches
wide. To check a tank of unknown size, use the following formula:
Capacity of Tank in Gallons = Width X Length X (Depth Minus One Inch)
When the inside dimensions of the tank are correct, the solution level is one inch below
the crossbar ledge.
c. Arrangement of Tank Units. The tank system usually consists of a master
tank containing three basic solution tanks. If a stop bath is used, there will be four
(figure 2-6). Water in the space between the developer and fixer sections is used for
rinsing or insertion of a stop bath solution tank, as well as for controlling temperature. A
separate washing tank, the same size, as the master tank is usually available. It may be
provided with a two-compartment cascade arrangement or it may be used as a single-
compartment wash tank. Washing arrangements should take into consideration a left-to-
right movement of films.